The present invention relates to the field of cutting and is concerned more particularly with a support bed that is used to hold sheet material such as plastic, fabrics and leather during work operations in which the material is penetrated by a cutting tool such as a reciprocating blade, a drill, a punch or other tool.
Prior art cutting machines that are used to cut limp sheet material such as fabrics for clothing or upholstery and similar materials have utilized bristled beds for supporting the sheet material as indicated in U.S. Pat. No. 245,150 issued in 1881 entitled "Machine for Cutting Cloth" and U.S. Pat. No. 3,548,697 issued in 1970 entitled "Penetrable Bed for Cutting Sheet Material". Bristles are ideally suited for cutting layups of sheet material with a reciprocating cutting blade because the blade can penetrate through the layup in cutting relationship with the material and into the bristled bed underlying the material without damaging or destroying the bed or blade. The bristles are generally flexible and readily separate at their free ends to accommodate the reciprocating cutting blade.
Also bristle support beds by virtue of their inherent porosity provide a convenient means for drawing a vacuum below a layup of sheet material to compress and hold the material in place during a cutting operation.
One problem that exists with prior art bristle beds arises with woven fabrics, especially those having a relatively coarse or open weave that permits threads to snag or catch on the bristles. In particular, knits can be severly damaged in appearance if one thread should become snagged on a bristle as the material is either spread or removed from a bed before or after a cutting operation.
Furthermore, in most bristle beds the free ends of the bristles do not lie in precisely the same plane due to slight differences in the length of the bristles and the manner in which the bristles are mounted in a supporting material or binder which holds the bristles in a closely packed array. With some bristles slightly longer than the others or projecting slightly above the others at the support surface, there is greater friction between the surface and the material, which hinders desired sliding movements. Snagging too is promoted by the uneven bristles.
Accordingly, it is a general object of the present invention to disclose an improved support bed for holding sheet material during a work operation and to disclose the method by which such a support bed is made.